Increasing level of CO2 in the atmosphere is known to enhance plant biomass accumulation, but its effect on reproductive allocation is little understood. Here, we combined meta-analysis and graphical vector analysis (GVA) to examine reproductive allocation (RA), i.e., the proportion of biomass allocated to reproduction, in plants as affected by elevated CO2. We were particularly interested in whether plants of different functional groups responded differently in RA to rising atmospheric CO2.
Results/Conclusions
Elevated CO2 had no significant effect on RA when averaged across all growth conditions and plant species. RA in different functional groups, however, differed in responding to elevated CO2. For example, RA in iteroparous crops increased significantly (+13.4%) at elevated CO2, although RA in semelparous crop species was unaffected by CO2 level. RA in wild grasses was reduced by elevated CO2 (-8.80%), whereas RA in cultivated grasses was unaffected. Wild and crop legumes had contrasting responses to elevated CO2 in RA. While wild legumes increased RA at elevated CO2, crop legumes had lower RA at elevated than at ambient CO2. Our results suggest that rising CO2 concentration in the atmosphere has the potential to greatly alter plant community composition and dynamics through its effects on allocation of biomass to reproduction.